A phase shifter, as one of very important microwave devices in microwave applications, has very wide applications in fields of radar, accelerators, communications, and instruments and meters. Generally, by inserting medium sheets, pins, and ferrites in the structure, change of waveguide coefficients may be achieved, and then an phase of the microwave may be changed.
The phase shifter has unique applications in synthesis and distribution of high-power microwave because it can change microwave phases. The faster the phase shift speed is, the higher the repetition frequency of system working may become. High-power phase shifters have already been studied. They place a ferrite or ferroelectrics of a certain geometric size in the waveguide, so as to change phase shift by changing material parameters of the ferrite or ferroelectrics using a peripheral high-voltage external circuit. Design of such phase shifters is highly demanding on the external circuit. To enable a fast phase shift, the external pulse voltage is generally required to be thousands of voltages; meanwhile, it is also highly demanding on a rising edge of the pulse. Besides, in order to provide a good transmission characteristic to the microwave, some other mediums are usually added in the structure of these phase shifters. Therefore, the design is relatively complex.
A common phase shifter is a dual-port microwave element, where the microwave enters from one port and outlets from the other port. Change of phase is achieved by adding a membrane sheet, ferrite and the like in a transmission segment. However, such prior art phase shifters that change ferrite material parameters through an external circuit have the following defects:
(1) limited phase shift. The design provided in current literatures can achieve a fast change of the phase in a very short time, but the change range of the phase is very small, which cannot achieve a 180° phase change.
(2) poor stability. The current phase shifter employs a method of external circuit control and achieves change of microwave phase by changing electric parameters or magnetic parameters of the material, which is highly demanding on the stability of external circuit voltage. The current design mostly captures a segment with a relatively good effect in a measurement result as the design result;(3) material limit. The currently existing phase shifter has a ferrite material or other material within the phase shifter, which increases design difficulty;(4) external circuit use. Through the external circuit, material parameters are changed and then phase size is changed. The voltage of the external circuit is usually thousands of voltages.
In the prior art, a single phase shifter has not achieved 180° phase shift between two adjacent microwave pulses, mainly because microwave transmission is limited. When the microwave passes through the phase shifter, the power will be lowered, and part of microwave will be reflected simultaneously; moreover, a ferrite-based phase shifter should guarantee a small reflection, a small loss, and a fast speed. All of the above are limiting factors.